“…In teleosts this hypothesis is mainly based on observations of correlative changes in environmental factors, hypothalamic nuclei and adenohypophysial activity (Peter, 1970 ;Ball et al, 1972). In addition, neurosecretory fibres, originating from the hypothalamus, are known to terminate on glandular cells of the adenohypophysis, on neighbouring capillaries, and on membranes of intracellular spaces (Zambrano, 1972 ;Peute et a/., 1976). These observations and the results of lesioning experiments (Peter, 1970) focussed attention on the nucleis lateralis tuberis (NLT) as the source of a gonadotropin releasing hormone (GRH) in teleosts.…”